1. Field of the Invention
This invention relates to computer motherboards, and more particularly, to an option setting device and method for use on a computer motherboard to provide various settings to the computer motherboard through software means instead of jumpers, thus allowing the computer motherboard to be more easily manufactured and used.
2. Description of Related Art
IBM-compatible personal computers (PC) are the most popular computer systems around the world. Earlier IBM-compatible PCs were constructed in compliance with the PC/XT and PC/AT standards. With technologies becoming more sophisticated and diversified, however, present computer motherboards are constructed in compliance with a great variety of standards. For instance, earlier CPUs were typically 4.77 MHz (megahertz) in speed, but today's high-end CPUs run at more than 300 MHz. Moreover, earlier CPUs were driven by a system voltage of 5 V (volt), but today's CPUs are driven by a system voltage of 3 V or even lower.
For compatibility reasons, many manufactures integrate the various standards on a single motherboard and provide jumper means (referred to as an option setting device in this specification) to allow the user to select the desired options. For example, the option setting device may allow the user to choose one frequency from 133 MHz, 166 MHz, 200 MHz, and 233 MHz as the clock rate to drive the CPU. Further, the option setting device may allow the user to choose between internal and external clock rates ad for the CPU and choose one voltage from 3.3 V and 2.8 V as the system voltage to drive the CPU. Beside the CPU, the motherboard may include various other components, such as a PCI (Peripheral Component Interconnect) interface, an AGP (Accelerated Graphics Port) interface, and a memory interface, for the installation of various expansion cards on the motherboard. These interfaces may run on various different clock rates and voltages that the user is required to set before operation.
In view of the foregoing requirements, a conventional computer motherboard is typically provided with a number of jumpers to allow the user to choose between all the available options. When there are too many available options, the motherboard may include such a great number of jumpers that it would be very difficult for ordinary users to implement the settings quickly and correctly. In the event of wrong settings, the computer motherboard may be inoperable or even suffer from system crash. It is therefore highly desirable to reduce or even entirely eliminate the jumpers and instead use software means to implement the settings.
FIG. 1 is a schematic system diagram showing the use of a conventional jumper-sharing scheme on a computer motherboard to help reduce the number of jumpers. As shown, the computer motherboard utilizing the jumper sharing scheme includes a clock generator 120 and a chip set 130, both of which are designed to share the same set of jumpers--a first jumper 111, a second jumper 112, and a third jumper 113. The clock generator 120 is used to generate a system clock signal for driving the motherboard, with the clock rate being dependent on the particular combination of the logic states at the FS1, FS2, and FS3 ports that is set via the three jumpers 111, 112, 113 to either the system voltage V.sub.cc (the high-voltage logic state) or the ground (the low-voltage logic state).
Moreover, the chip set 130 can be used to set the clock rates respectively used to clock the CPU (not shown), the AGP interface (not shown), and the PCI interface (not shown), which are dependent on the particular combination of the logic states at the HA1, HA2, HA3 ports that are also set via the three jumpers 111, 112, 113 to either the system voltage V.sub.cc or the ground. The clock generator 120 and the chip set 130 can share the same set of jumpers 111, 112, 113 because the clock rates for the CPU, the AGP interface, and the PCI interface are related to the system clock rate generated by the clock generator 120.
Therefore, the jumper-sharing scheme can help reduce the number of required jumpers on the computer motherboard. Since the HA1, HA2, HA3 ports of the chip set 130 may not be set to the same logic states as the FS1, FS2, FS3 ports of the clock generator 120, an adapting circuit composed of three tri-state buffers 141, 142, 143 and two inverters 151, 152 is provided between the jumpers 111, 112, 113 and the chip set 130 to alter the logic states to the ones desired for the chip set 130.
It is to be noted that the adapting circuit shown in FIG. 1 is only an example; the actual configuration is dependent on the specifications of the integrated circuit being used as the chip set 130. Furthermore, the chip set 130 is provided with a REST port, which is connected to receive a DRST signal. The DRST signal is also used to control the tri-state buffers 141, 142, 143 in such a manner that when it is switched to a first logic state, for example a low-voltage logic state, it switches the buffers 141, 142, 143 to the conducting state, thereby allowing the transfer of the logic voltage states set by the three jumpers 111, 112, 113 respectively to the HA1, HA2, HA3 ports of the chip set 130; and when switched to a second logic state, for example a high-voltage logic state, it switches the buffers 141, 142, 143 to non-conducting state. In the latter condition, the HA1, HA2, HA3 ports of the chip set 130 can be used as output ports for address signals.
The foregoing jumper sharing scheme allows the clock generator 120 and the chip set 130 to share the same set of jumpers 111, 112, 113 to receive the user-defined settings. One drawback to this scheme, however, is that when other makes of devices with different specifications are used as the clock generator and the chip set, the adapting circuit (i.e., the buffers 141, 142, 143 and the inverters 151, 152) between the jumpers 111, 112, 113 and the chip set 130 may have to be redesigned in compliance with the new specifications of the clock generator and the chip set.
The manufacture of the motherboard would be therefore quite cost-ineffective. Moreover, if an advanced device having a software frequency programming capability is used as the clock generator 120, the scheme of using jumpers to set options would not allow such a clock generator to be fully utilized in its advanced functionality.
As a summary, the prior art of FIG. 1 has the following disadvantages in manufacture and utilization.
(1) First, the prior art is quite cost-ineffective for the suppliers to manufacture, in that when another make of clock generator and chip set are used, the adapting circuit may have to be totally redesigned so as to allow the new clock generator and the new chip set to share the same set of jumpers.
(2) Second, the scheme of using jumpers to set an advanced clock generator having a software frequency programming capability would not allow the clock generator to be fully utilized in its advanced functionality.
(3) Third, the scheme of using jumpers to provide various settings to the motherboard would be user-unfriendly to most computer users and could easily result in wrong settings.